Forcing Sdram Commands; Force Precharge All - Analog Devices SHARC ADSP-214 Series Hardware Reference Manual

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The following steps are required when using self-refresh mode.

mine if the SDRAM has already entered self-refresh mode.

3. Optionally: set the

4. Optionally: clear the

5. SDRAM access occurs the SDRAM exits from self-refresh mode

The minimum time between a subsequent self-refresh entry and

exit command is the t

during any external port DMA, the SDC grants the request with

Forcing SDRAM Commands

The SDC does have some specific bits which can be used to aid in debug

and in specific system solutions.

Whenever an auto-refresh or a mode register set command is issued, the

internal banks are required to be in idle state. Setting bit 21 (=1) forces a

precharge all command to accomplish this. If the precharge all command

is not issued, the auto-refresh and mode register set commands can be ille-

gal depending on the current state.

Note that it is a good practice always to perform a force precharge all com-

mand before a forced refresh/mode register command.

ADSP-214xx SHARC Processor Hardware Reference

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bit to enter self-refresh mode

bit in the SDRAM status register (

bit to freeze

cycle. If a self-refresh request is issued

cycle and continues DMA operation afterwards.

bit to re-enable

External Port

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